Occupant protection systems have an ignition circuit system that has at least one ignition circuit for activating a restraint device. Today's ignition circuit monitoring is made up of shunt detection at the supply terminals of the ignition circuit, and a resistance measurement of the ignition circuit loop. In addition, a coupling test is implemented in order to recognize whether an ignition circuit is coupled to another ignition circuit or to other inputs/outputs of control devices.
An object of the present invention is to further improve the existing art, and to integrate it in the ignition circuit or system ASICs in a manner that uses less space.